THURSDAY, Jan. 14 (HealthDay News) -- An agreement in principle on the landmark overhaul to the U.S. health care system could come as early as Friday, lawmakers said Thursday.

The agreement in principle, which would cover major issues such as how to pay for health coverage and how many Americans could receive it, would then go to the Congressional Budget Office for its estimates. Only after the budget office reviews the proposal can the House of Representatives and Senate take a final vote and send the bill to President Barack Obama for his signature.

"We're shooting for tomorrow," House Ways and Means Committee Chairman Charles Rangel (D-N.Y.) told reporters Thursday. "We hope to have the whole thing, as much as we can have [for the budget office] to be able to start working."

Following months of heated debate, negotiations picked up speed Wednesday, when lawmakers met from midmorning until early evening at the White House, trying to iron out differences between the Senate and House versions of the bill. Negotiations resumed at the White House Thursday, and Rangel made his prediction after speaking with House Speaker Nancy Pelosi (D-Calif.) and other Democratic leaders, the AP said.

The plan would expand coverage to more than 30 million people who lack insurance, prohibit insurers from denying coverage to those with existing medical conditions, and attempt to control soaring health-care costs.

A major obstacle -- a proposal to tax high-value medical plans -- was apparently resolved in private negotiations with union leaders Thursday, and the tentative settlement was to be put before Congressional leaders later in the day, said union and Democratic officials speaking anonymously, the AP reported.

House Democrats had opposed the tax for union members, which was part of an early Senate version of the bill. But Obama -- based on a consensus of economists -- favored the tax as a way to encourage workers to take less expensive coverage, thereby driving costs down, the news service said.

Details of the preliminary agreement were not made public, the AP noted.

Karen Davis, president of the Commonwealth Fund, a private foundation that seeks better health care for all Americans, called word of a pending agreement "very good news."

"It's an embarrassment in the 21st century that people who need medical care can't get it," she said. "We are the only major country without a system for everyone."

Skyrocketing medical costs have hurt increasing numbers of American families, the workforce and the entire health-care system, Davis said. The new bill, which she described as "pragmatic and uniquely American," is a "terrific opportunity to transform the system."

Democrats, explaining the urgency of the health-care negotiations, said more Americans are losing health insurance every day.

"If we do nothing, if, God forbid, this bill crashes and burns, we could have 60 or 80 or 100 million people without insurance," Rep. Eliot L. Engel (D-N.Y.) told The New York Times.

As the health-care reform talks dragged on, from summer into winter, public opinion polls showed that American support for the bill began flagging. Democrats have expressed concern that further delays would give Republicans more time to strengthen their offense against the proposed legislation.

The bill's twists and turns through the halls of Congress have led to many alterations, including the loss of a government-run public option -- considered by some to be one of the better ideas for cutting costs.